What is the total cost of a secondary suite conversion including fire separation in Toronto?

A legal secondary suite conversion in Toronto including all fire separation requirements costs between $60,000 and $140,000 in 2026, with most complete projects landing in the $75,000 to $110,000 range. Fire separation alone — often underestimated by homeowners — accounts for $8,000 to $20,000 of that total, and it is non-negotiable for a legal basement apartment.

The fire separation requirements under the Ontario Building Code are extensive and specific. You need a 1-hour fire-rated separation between the basement suite and the rest of the house, which in practice means two layers of 5/8-inch Type X fire-rated drywall on the ceiling separating the units, fire-rated drywall on all shared walls, fire caulking (intumescent caulk) at every penetration where pipes, wires, and ducts pass through the fire separation, fire dampers installed in any HVAC ductwork that crosses the separation ($200 to $500 per damper, and a typical home may need 4 to 8), and fire-rated doors with self-closing hardware at every entrance to the suite ($300 to $800 per door installed). The materials and labour for comprehensive fire separation run $8,000 to $15,000 for a straightforward layout, or up to $20,000 for homes with complex ductwork, multiple penetrations, or difficult ceiling access.

Beyond fire separation, the major cost components of a secondary suite include the kitchen ($10,000 to $25,000 for cabinetry, countertops, appliances, plumbing, electrical, and range hood vented to exterior), the bathroom ($20,000 to $40,000 depending on whether plumbing rough-in exists or you need to break and repair the concrete floor), separate entrance ($3,000 to $15,000 depending on whether an exterior entrance exists or needs to be created), egress windows for every bedroom ($3,000 to $8,000 per window), and HVAC for the suite ($4,000 to $10,000 for a ductless mini-split system or dedicated ducted heating and cooling).

The electrical scope for a secondary suite is substantial. The suite needs its own circuits for kitchen appliances (dedicated 20-amp small appliance circuits, dedicated stove circuit, dedicated refrigerator circuit), bathroom, lighting, and outlets throughout — this typically requires a subpanel and runs $5,000 to $12,000 for the electrical work alone. All work must be done by an ESA-Licensed Electrical Contractor. Interconnected smoke and carbon monoxide detectors must be installed on every level and outside every sleeping area in both the suite and the main dwelling, with all alarms sounding simultaneously when any one is triggered.

The City of Toronto permitting process for secondary suites involves several steps and fees. A building permit based on construction value typically costs $3,000 to $5,000. You may need a zoning review ($300 to $500) to confirm your property is eligible — Toronto's city-wide zoning now generally permits secondary suites in most residential zones, but there are still requirements around parking, lot coverage, and unit size that your property must meet. If a minor variance is needed, a Committee of Adjustment application runs $5,000 to $10,000 including professional fees. Factor in 3 to 6 months for the approval process before construction begins.

Many homeowners overlook the ongoing compliance costs of a legal secondary suite. You will need annual fire equipment inspections, proper insurance coverage (your home insurance policy must be updated to reflect the rental unit — failure to disclose voids your policy), and compliance with the Residential Tenancies Act. However, with GTA basement apartments renting for $1,200 to $2,200 per month, the investment typically pays for itself within 3 to 7 years while significantly increasing your property value. The critical point is that only a legally permitted secondary suite delivers these benefits — an unpermitted basement apartment carries fines, insurance voidance, and orders to remove the work.